Atherosclerosis is a disease in which plaque builds up inside arteries. Atherosclerosis is the usual cause of heart attacks, strokes, and peripheral vascular disease—together called “cardiovascular disease.” Cardiovascular disease is the leading cause of death in the United States and worldwide. Atherosclerosis can affect any artery in the body, including arteries in the heart, brain, arms, legs, pelvis, and kidneys. As a result, atherosclerosis may cause many different diseases, based on which arteries are affected. One of the most common forms of atherosclerosis, and the one that causes the most deaths, is atherosclerosis of the coronary arteries, which supply the heart with blood—referred to as “coronary artery disease” or “CAD.”
Detection of coronary atherosclerosis is challenging, due to the small size of the coronary arteries, the motion of the beating heart, and obscuring signals from adjacent myocardial (heart muscle) tissue. The current gold standard for detecting CAD, and the procedure used most often, is cardiac catheterization angiography. Cardiac catheterization with angiography involves inserting a thin, flexible catheter into an artery in the leg or arm, advancing the catheter through the artery to one of the coronary arteries, and taking radiographic pictures of the coronary artery (angiography). Blockages in the coronary artery (or arteries) are visible on a live X-ray screen.
One of the shortcomings of cardiac catheterization with angiography is that it only reveals the outlines of the flow space inside the coronary arteries with narrowed (stenotic) arterial segments or blockages. It does not provide any additional information about the atherosclerotic plaque, such as the extent, content, and biology of the plaque. Another shortcoming is that cardiac catheterization with angiography cannot detect early atherosclerotic plaque, which builds up inside the arterial wall but does not yet protrude into the arterial lumen. Thus, it would be beneficial to have improved devices and methods for detecting atherosclerosis in coronary arteries and/or other arteries in the body.